On Testing

Abstract

A theory is an agenda for empirical work. With the foregoing chapters having presented the theoretical developments, it is now time to turn to the empirical aspects. The word agenda has been used deliberately. The theory that has been developed yields a number of assertions that are amenable to testing, and it demands measurement of its crucial variables. Such measurement will take much time and effort and cannot be dealt with exhaustively in this book. In fact, the remainder of the book will deal only with the initial empirical steps. These steps consist of enumerating important predictions and examining them in the light of empirical results obtained by others. Chapter 8 will present original evidence from data available in the United States.

As we learn from our mistakes our knowledge grows, even though we may never know — that is, know for certain. Since our knowledge can grow, there can be no reason for despair of reason. And since we can never know for certain, there can be no authority here for any claim to authority, for conceit over our knowledge, or for our smugness.

—Karl R. Popper (1963)